Just like few other people here, I tried to upgrade my account to plus. Entered all my personal details and paid for it. I have realized only after the payment was successful that the payment page was linked to another random user's session and I have paid for their upgrade due to this massive bug.
Can't even cancel because my account doesn't have plus due to the error. There is no support to contact. My bank account has been charged and that's the only proof I have.